A sealed ampoule of pressurized supercritical liquid Tungsten Hexafluoride.  Purity is 99.5%+.  This amazing sample will phase change when heated to 169.8°C.  Let it cool down below 169.8°C and it will condense back into the liquid phase again.  This is truly an amazing sample.  It is not recommended to heat these ampoules to the critical temp because they could burst. This fits perfectly inside the included 1 dram vial for display.